Impact of piglet birthweight and sow parity on mortality rates, growth performance, and carcass traits in pigs

ABSTRACT A total of 5502 piglets from 435 sows were selected for evaluation of the effect of piglet birthweight and sow parity on mortality rate (MR), growth performance, and carcass traits in pigs. Piglets were distributed into one of eight categories according to their weight (&lt;600, 601-800, 801-1000, 1001-1200, 1201-1400, 1401-1600, 1601-1800, and &gt;1801 g) and sows were classified according to parity (1-5). The maximum MR during lactation (day 0 to day 21) was found in category &lt;600 g, whereas the lowest was observed in categories ≥1401 g. Pigs with greater body weight (BW) at birth were equivalently greater until 59 days of age. Average daily weight gain (ADG) was improved by increasing piglet birthweight between 0 and 21 days as indicated by a linear regression effect. After weaning, this effect was reduced up to 168 days, indicated by a quadratic, as opposed to linear, regression effect. The increase in growth rates corresponded to improved lean meat content and hot carcass weight. Increasing sow parity corresponded to a quadratic improvement of BW and ADG during lactation, but not after weaning. However, the improved pre-weaning performance was concomitant with a linear increase of within-litter BW and ADG variation. No effect of parity was observed on carcass traits. Piglet birthweight and sow parity influence litter postnatal development, mainly during early life. After weaning, these effects are less evident with a minor impact on carcass traits.摘要 本研究选取435头母猪所产的5502头仔猪，旨在评估仔猪初生重与母猪胎次对仔猪死亡率（MR）、生长性能及猪胴体性状的影响。研究按照初生体重将仔猪划分为8个组别：<600g、601~800g、801~1000g、1001~1200g、1201~1400g、1401~1600g、1601~1800g及>1801g；同时按照胎次（1~5胎）对母猪进行分组。结果显示，哺乳阶段（0日龄至21日龄）的最高死亡率见于<600g组仔猪，最低死亡率则见于≥1401g组仔猪。初生体重较高的仔猪，其体重在59日龄前均保持显著优势。线性回归分析表明，仔猪在0~21日龄阶段的平均日增重（ADG）随初生体重增加而显著提升；断奶后该效应逐渐减弱，直至168日龄时，回归效应由线性转变为二次型。生长速率的提升与瘦肉率及热胴体重的改善呈正相关。母猪胎次的增加与哺乳阶段仔猪的体重及平均日增重呈二次型改善关系，但该效应在断奶后不再显著。然而，断奶前生长性能的改善伴随同窝仔猪间体重及平均日增重变异程度的线性升高。母猪胎次对胴体性状无显著影响。综上，仔猪初生重与母猪胎次可影响同窝仔猪的产后生长发育，该影响主要集中于生命早期阶段；断奶后，上述效应逐渐减弱，对胴体性状的影响亦相对有限。